Internal electron donors are one of the components of Ziegler Natta catalysts for the polymerization of propylene. One of these known donors is called AB (or 4-[benzoyl(methyl)amino]pentane-2-yl benzoate or 4-(methylamino)-pentan-2-ol dibenzoate), a so-called non-phthalate internal donor of the benzoate type. A synthesis of AB is disclosed in EP 2 867 264 B1 and consists of the following three steps: step 1) the formation of a ketoenamine from acetyl acetone; step 2) the reduction of said ketoenamine to an amino alcohol using sodium metal (Na) in an isopropanol-tetrahydrofuran solvent mixture; and step 3) the benzoylation of the amino alcohol to AB using a benzoyl chloride as reagent and pyridine as a base and methylene dichloride as a solvent. After steps 1) and 2) the intermediate products are isolated and purified for use in the next step, being steps 2) and 3) respectively. The overall yield of this known process is approximately 54%.
It is an object of the present invention to propose an improved and alternate process for the synthesis of dibenzoate compounds, such as 4-(methylamino) pentan-2-ol dibenzoate (AB donor). It is an object of the present invention to develop an economical process for the production of dibenzoate compounds, such as AB donor, that can be used on large scale without the use of pyrophoric reagents.